1. Field of the Invention
The present invention relates to a lens-fitted photographic film package, and more particularly to a lens-fitted photographic film package in which the inspection process to determine reusability of the parts is simplified and thus the efficiency of inspection is improved.
2. Related Art
Lens-fitted photographic film packages (hereinafter called simply film packages) are now on the market, for example under the trademark "Quick Snap". Each such film package is a single-use camera designed to make it possible to take pictures whenever desired without buying or carrying about an expensive and heavy camera. The film package is pre-loaded with photographic film in the factory, so that the user can take photographs without the need for film loading. After the exposure of all available frames of the pre-loaded film, the user is not required to rewind and unload the film. The user has only to forward the whole film package to a photofinisher or an agency for development of the exposed film.
The exposed film is removed from the film package for development and printing in a photofinishing laboratory, and the developed film and the consequent photographic prints are returned to the user. Emptied bodies of the film packages are reused or recycled.
Because of these properties and the manner of use of the film packages, it is necessary to minimize production costs of the film package. For this reason, most essential parts of the package body are formed from resin materials. When assembly, most parts are attached to each other by snap-in engagement between a hook and a hole, making use of the elasticity of the resin material.
Not only for reducing production costs, but also for saving natural resources, it is desirable to reuse the parts of the package body. In order to reuse the parts, the emptied film packages are recovered and disassembled into their individual parts. The parts are sorted out between those directly reusable and those whose material is recyclable. The directly reusable parts are returned to the assembling process of the film package. The parts to be recycled are sorted according to the kind of material, and suitably processed, for example, crushed, melted and/or formed into pellets.
It is desirable to reuse the parts of the package body or to recycle the materials thereof not only to save natural resources but also for environmental protection. But before any parts can be reused, it is necessary to inspect them for reliability and reusability. Most parts of the package body are made from PS (polystyrene) resin because of the superior moldability and low cost thereof. However, it is known in the art that PS resin is permanently deformed or heat distorted at a temperature of about 85.degree. C. For example, the interior temperature of a car can reach this under a burning sun. Therefore, if the film package is left in such a car, those parts of the film package which are made from PS resin and elastically deformed in the assembled state will be permanently distorted, and the elasticity thereof will be decreased. The heat distortion may occur even at a temperature about 65.degree. C. if the film package is left for a sufficiently long time in such a hot place.
If the heat-distorted parts were directly reused, because those parts lose necessary elasticity, troubles would arise. For example, the snap-in engagement would be loose, the required optical quality would not be achieved, or the light imperviousness of certain portions would be insufficient. For this reason, for the parts to be directly reused, it has been necessary to measure and inspect these parts in various ways, in order to judge their suitability for reuse. For example, the dimensions of each part are measured with a precision of about 0.1 mm, or the elasticity of the part is tested. Such measurement or inspection processes require much time and labor.